1. Field of the Invention
The present invention relates to a load detection element for detection of a load applied to a vehicle seat, the load detection element being of such a type wherein a longitudinally elongated strain plate member is provided, which extends along the fore-and-aft direction of the vehicle seat and wherein a load detection device having a strain gauge is provided under the seat such that the strain gauge detects an amount of deflection of the strain plate member which is caused by a load applied to the seat and gives a numerical data indicative of the deflection amount. In particular, the invention is directed to a structure for securing this kind of load detection element between the bottom of vehicle seat and a floor of the vehicle.
2. Description of Prior Art
Various automatically controlled functions and mechanisms have been increasingly incorporated in vehicle or automobiles, including safety devices such as air bags for protecting passengers against a great impact automatically in response to a collision. With such automated control innovations, there have been also found technical improvements to a passenger detection system for detecting the presence and absence of a passenger or driver in a seat of vehicle in advance before actuating or stopping the associated mechanical elements to automatically control various functions and mechanisms built in the seat.
Normally, the passenger detection system or a load detection structure employs sensors which can detect a load in terms of presence and absence of passenger on a seat, and recent high-tech control technology has developed sensors capable of detecting a degree of load whether the passenger is an adult or a child as with air bag control system for instance.
In most cases, a slide rail device, which typically comprises a lower rail and an upper rail slidably fitted in the lower rail, is provided under the seat to thereby allow for free forward and backward movement of the seat. In that case, a known load detection structure to be provided between the slide rail device and the seat is such that a load detection means used therein comprises: support leg members for supporting those slide rail device and seat upon the floor of a vehicle; and strain elements of deflectable property, each of which is pivotally connected with each of the support leg members at the pivotal end portion thereof and firmly secured to the lower rail of the slide rail device at the securing portion thereof, as disclosed for example from the U.S. Pat. No. 6,520,023.
Recently, it has been required that the support leg members of the load detection structure should be able to be mounted on various uneven surfaces of the vehicle floor which has been found in different kinds of vehicles and automobiles due to their own different designs.
Further, normally, the securing portion of each strain element is firmly secured to the lower rail by means of rivet pins. However, the riveted ends of the rivet pins which project in the lower rail, which undesirably limits the fore-and-aft movement range of the upper rail slidingly movable in and along the lower rail.
In view of the above-stated drawbacks, it is therefore a primary purpose of the present invention to provide an improved structure for securing a load detection means for detecting a load applied to a seat in a vehicle seat, which is greatly simplified in structure with reduced number of constituent elements and effective in avoiding undesired increase in height of the seat and reducing projected portions between a vehicle seat and the load detection means to thereby allow the seat to be mounted on uneven floor, while preventing damage and breakage of the load detection means when an excessive great load is applied thereto.
In order to accomplish such purpose, in accordance with the present invention, in combination with a floor of vehicle, there is basically provided a structure for securing a load detection means under a bottom side of the vehicle seat and in a support leg means for supporting the vehicle seat upon the floor of vehicle, the support leg means including; a bottom wall; one end facing to a side forwardly of the vehicle seat; and another end facing to a side backwardly of the vehicle seat,
wherein the load detection means is adapted to detect a load applied from an occupant on the vehicle seat and comprises: a resiliently deflectable strain means having an elongated body extending along a fore-and-aft direction of the vehicle seat; an upper side facing to the bottom side of the vehicle seat; a lower side facing to the bottom wall of the support leg means; a securing end portion; a pivotal end portion; and a deflectable portion defined between the securing and pivotal end portions; and a strain gauge means fixedly attached to the deflectable portion,
wherein the resiliently deflectable strain means is rotatably journalled at the pivotal end portion thereof by a pivot pin within the support leg means, such that the securing end portion of the resiliently deflectable strain means is disposed adjacent to either of the one and another ends of the support leg means, whereas the pivotal end portion of the resiliently deformable means is oriented to a center of the support leg means,
wherein a hole is formed in the bottom wall of the support leg means at a point adjacent to either of the one and another ends of the support leg means,
wherein a first securing pin is provided in the securing end portion of the resiliently deflectable strain means at a point near to either of the one and another ends of the support leg means, the first securing pin having an end fixedly connected with the bottom side of the vehicle seat, and
wherein a second securing pin of a fusible property having a head portion and an end is provided in the securing end portion of the resiliently deflectable strain means at a point distant from either of the one and another ends of the support leg means, such that the end of the second securing pin is fused in the bottom side of the vehicle seat, while the head portion of the second securing pin is disposed on the lower side of the resiliently deformable means, with one predetermined space given between the head portion of the second securing pin and the bottom wall of the support leg means.
Accordingly, as only the head portion of first securing pin projects, there is no other projection under the support leg means, thereby allowing the seat to be mounted on any uneven floor, and further, when an excessive great downward load is applied to the vehicle seat, causing the resiliently deflectable strain means to deflect downwardly to a level in excess of the one predetermined space, the head portion of the second securing pin is brought to contact with the bottom wall of the support leg means, thereby protecting the deflectable portion of the resiliently deflectable strain means against a deflection in excess of a tolerable range in which the strain gauge means works for detection of the amount of deflection.
In one aspect of the present invention, a slide rail device may be provided between the load detection means and the bottom side of vehicle seat, the slide rail device comprising: a lower rail fixed to the bottom side of vehicle seat, the lower rail having a flat bottom surface and one end; and an upper rail slidably fitted via a plurality of rollers in the lower rail, wherein the plurality of rollers are movably interposed between the flat bottom surface of the lower rail and the upper rail, In this mode, a first hole may be formed in the flat bottom surface of the lower rail at a point near to the either of the one and another ends of the support leg means; a second hole may be formed in the flat bottom surface of lower rail at a point distant from either of those one and another ends of support leg means; a hole formed in the bottom wall of support leg means in alignment with the first hole; such that the end of the second securing pin is fused and fixed in the second hole so as to be flush with the flat bottom surface of lower rail, while the head portion of the second securing pin is disposed on the lower side of the strain element, with a second predetermined space given between the head portion of the second securing pin and the inner surface of the bottom wall of the support leg means; the end of the small-diameter portion extending upwardly through the securing end portion of resiliently deflectable strain means and is riveted to the second hole of the lower rail.
Accordingly, this aspect of the invention provides an extended flat surface region on which the rollers are smoothly rolled and moved on and along the lower rail, so that the range of forward and backward movement of the upper rail along the lower rail (18) is increased.
Over various effects and advantages of the present invention will become apparent from reading of the description hereinafter, with reference to the annexed drawings.
FIG. 1 is a partly broken schematic side elevational view showing the stated where load detection structures of the present invention are provided in a vehicle seat;
FIG. 2 is a partly broken, exploded perspective view showing a principal part of the load detection structure;
FIG. 3 is a fragmentary sectional view of the principal part of the load detection structure; and
FIG. 4 is a partly broken front view showing the principal part of the load detection structure.